The aim of this study is to further investigate estrogen, corticoid, and gonadotropin abnormalities in obesity: (1) 24-hour mean plasma estrone (E1) and estradiol (E2) are evaluated in obese men but not obese women. The high estrogen levels in the men cause hypogonadotropic hypogonadism (FSH, relatively low LH, free and total testosterone). Giving dexamethasone (D) normalizes the hormone levels (suppresses adrenal secretion of Delta 4-androstenedione (Delta), the main substrate of aromatization of estrogens). These studies will be extended in number and duration; we will also test whether the aromatase inhibitor testololactone similarly normalizes hormone levels. (2) D administration greatly decreases plasma E1, but not E2, in obese women. This suggests a large contribution of aromatization to E1 levels. The absence of elevated E1 levels despite this remains unexplained. It is not known whether nonobese women respond similarly to D suppression and this will be studied. (3) Weight loss unexpectedly increases plasma E2 in obese men. We will study the effects of duration and degree of weight loss, and initial and final weight, on this phenomenon. The effect of weight loss on plasma estrogen in obese women will also be studied. (4) Obese women have depressed 24-hour mean plasma LH and LH/FSH ratio, resembling the "slow-GnRH-pulsing syndrome" in monkeys; these monkeys do not ovulate (pertinent to frequent anovulation in obese women). 24-Hour plasma LH profile will be studied in normal and obese women to document LH-pulsing frequency (=GnRH pulsing frequency). (5) The sex difference in plasma E2/E1 ratio (women greater than men) is accentuated in obesity. Kinetics of E1 going to E2 and vice versa interconversion will be studied with tracers, using a newly devised protocol, under basal conditions and in two states of acute elevation of the E2/E1 ratio (infusion of E2 loads; E1 suppression by D). (6) Evidence has been found of a sex difference in adipose-tissue content of estrogen and corticosteroid receptor (women greater than men). In vitro quantitation of both types of receptors will be done and an indirect in vivo measure of estrogen receptor content will be made using tamoxigen: this drug increases urinary excretion of radioactivity from estradial tracers in women (blocks uptake by tissue receptor); if men have less receptor, tamoxifen should have less effect on tracer excretion.